Exhaust steam heater



Nov. 3, 1931. .J. N. WY NDHAM ET AL 1,830,535

EXHAUST STEAM HEATER Filed Oct. 9. 1929 Patented Nov. 3, 1931 UNITED PATENT OFFICE JAIQES w am-ielr inseam Lawson warmers F Q a IF-E; WALES s an HEATER,

- Qatari as paras. 2a finia in, 3 15. n i Gr B t ie wer 2 This invention relates to'exhaust steam heatersand ts ob e ct to provide animmg one or more heating unitshav-in'g a bank,

or banks, of parallel, or substantiallyparallel, tubes, and headers with which the said m tubes communicate so that the exhaust steam to be reheated is conveyed-by the said'h'ea'd ers and tubes in parallel, or substantially parallel, streams, through a heating space where in the said headers and tubes are exposed to boiler flue gases or like heating'mediumi- A further fe'atureof our inventionfis to provide an exhauststeam heater comprising one or more heating units having a cora bined inlet and outlet'header, a'transferj or return header, a bank or row of outgoing tubes leading from the said header, a'bank' or row of returntubes entering the saidheader, and a transfer or returnheader uniting the free ends of said outgoing and re turn tubesJ f 1 Y In accordance with another feature ol the invention, the exhaust steam heater com prises one ormore heating units having superposed rows of steam tubes arr angedwith headers thereforintho path 9f boiler flue gases or like heating mediung'the tubes of each row being staggered orplaced outof alignment with respect to the tubes of the row rows there-below:

More speeifiea ly, our exhaust he er has one or more heating units arranged in the upper part of a boiler uptake and comprising a bank, or banks, of parallel or substantially parallel, steam tubes, and head ers with which the said tubes are connected so that both the headers and tubes are completely enclosed within the uptake and ex tend across the whole or the most part of the cross-section thereof. Preferably the heating unit or units is or are arranged above an air heater in the uptake.

A preferred embodiment of our invention, as applied to an exhaust steam heater for use in the uptake of marine boilers with the Howden forced draft system, will now be proved construction and arrangement theredescribed,;by Way of example, with reference to the annexed drawings, in which:

Fig, l'is a side View of the exhaust steam heater with the boiler uptake casing in sec-. tion.

Fig. 2 is a plan view of the heater' with the uptake easing removed. Fig. 3 is a cross-sectional View of the heater, taken on the line A'B '(Fig. 2).

Referring-tothe drawingsz- The boiler uptake casing 1 accommodates in known manneran air heater having vertical air heating tubes 2 through which the boiler flue gases pass upwards. Above the upperends of the tubes 2, the exhaust steam heater described hereinbelow is located, sufficient clearance being left'between-the heater and the upper ends of the tubes 21:0 permit the unobstructed passage of the flue gases through and around the whole heater as hereinatter explained. p

The exhaust steam heater comprises two similar heating units a and b connected'in series by elbow pipes 3. Each units comprises F acom'bined inlet and outlet header 4, and a transfer or return header 5, both of these headers being bozg shaped. Each of the com bined inlet and outlet headers 4 is provided with a dividing wall 6 (see Fig, 3) which separates the interior of the header into a lower space 7 andan upperspace 8. In the header 4' of the heating unit a, thelower space 7 constitutes the inlet chamber of the header and communicateswith apip'e 9 whereby the exhaust steam for reheating enters. The upper space 8 of the unit a, onth'e other-hand, commtmicates (see Fig. '3) with the elbow pipe lwhereby the exhaust'steam passes putwards from the'unit a tothe unit 6'." This arrangementis' reversed in respect of the heating unit I), the upper space of the header 4: in this case constituting the inlet chamber into which leadsthe elbow pipe 3 and the corresponding lower space constituting the out let chamber fromwhich'the reheated exhaust steam escapesby the outlet pipe 10. In contrast to the above described partitioning of the headers 4-, the interior of both transfer or-return headers 5 is left plain,.i.e., is not divided into separate compartments.

the headers, or by screwing them into the headers.

The complete exhaust steam heater constituted by the headers 4 and5, tubes 11 and 12, and elbow pipes 3. is supported above the air-heating tubes 2 by wrought iron or like metal clips each of which is formedby a bottom strip 13 of angle section secured at the ends to the uptake casingwl. and a keeper strap 14 which extends over the tubes 11, 12

and is bolted tothe corresponding bottom strip 13.

The direction of flow of the exhaust steam through the heater is shown in Figs. 1 and 2 y the arrows. As will be apparent from the foregoing; the steam-to he reheated flows from the lower space 7 of the header 4 of the unit a, through the six bottom tubes 11, thence returning by way of the transfer head er 5, through the five top tubes 12 tothe upper space 8 of the first mentioned header 4. Thereafter. thepartially reheated steam passes over the elbow pipes 3 into the upper space of the header 4:- of theunit 2'), and thence throu h the top tubes 12. transfer header 5. and bottom tu es 11 into the lower space of the last mentioned header 4 from which the completely reheated steam escapes by. the outlet pipe 10.

It will be seen from Fig. 3 that the top tubes 12 of the heating units are arranged in staggered relationship with respect to the bottom tubes 11, i. e., a tube 12 is arranged directly above each space between the tubes 11. By this arrangement. the top and bottom rows of exhaust steam tubes exert a baflle efl'ect on the ascending flue gases,-suffic ent'to' obtain'a more thorough exchange of heat between the flue gases-and exhaust steam than is obtainable by arranging each tube 12 of the top row directly abovea tube ll f thebottom row. V

Thereheated steam may bev used for any desiredpurpose in kn own manner, as for instance, in'marine work, for heating. cabins or for the low pressure stage of the. engine.

It will be understood thatvarious modifications may be'made in the invention without departing from the scope of the claim. For example, three or more heating units, instead of two units as described, can be connected in series and an exceptionally large heating surface is thereby. provided for the steam. Any convenient method may be used for connecting theheatingunits together. An alternative method to that previously described consists of fitting to the outletof one unit a male joint which isadapted to register with a female .joint on the inlet of the adjacent unit, or vice versa, the two being secured to gether with tie bolts which pass through the two units. The joint is of course made steam tight in well known manner.

Our invention is particularly adapted for use with the well known Howden forced draft system, one mode of using the invention with which system has been described above. and is also adapted for use with boilers fitted with high pressure superheater .where the exhaust steam heating elements have to be placed high in the boiler uptakes. T

We claim: The combination with a boiler of an'exhaust steam heater mounted in the uptake adjacentthe outlet ends of flue gas tubes,

said heater comprising, two interconnected heating units, each unit comprising a divided header forming inlet and outlet compartments for the steam to be heated,,a first row of parallel steam tubes let into the inlet compartment, a second row of parallel steam tubes-let into the outlet compartment. said first and second rows each extending in planes substantially parallel to that containing the outlet ends of the flue gas tubes whereby the flue gases impinge on the steam tubes immediately after leaving the flue gas tubes and without changing their direction of flow, a single compartment header uniting the free ends of the steam tubes in said'rows. but the first row of steam tubes in one unit being nearer the outlet ends of the flue gas tubes than the second row, and the second row of steam tubes in the other unit being nearer the outlet ends of the flue gas tubes than the first row in that unit, whereby the steam is caused to flow. firstly in a row ofsteam tubes nearer the outlet ends of the flue gas tubes, then in two rows in series further away from these outlet ends, and finally in a row nearer these outlet ends, the steam in the final stage, therefore being heated by the hottest flue gases.

Intestimony whereof we afiix our signatures.

JAMES NEWBY WYNDHAM. STEPHEN LEYSHON WYNDHAM. 

